Large urban lakes are usually the landscape core of cities.

The recommended method is to use ecological restoration theory as a guide to construct a complete wetland and aquatic ecosystem, using aquatic plants, aquatic animals, and aquatic microorganisms to absorb, fix, and gradually transfer nitrogen and phosphorus from water, and to perform aerobic and anaerobic decomposition of organic matter, so as to restore the natural purification function of water and achieve excellent water quality.

Depending on the water quality, pre reservoirs, ecological ponds, constructed wetlands, or high-efficiency water treatment units are used to purify the supplementary water, in order to minimize the pollution of the lake caused by the supplementary water.

For certain branches of lakes with particularly high water quality requirements, constructed wetlands or high-efficiency water treatment units can be used for enhanced purification to further improve water quality.

Before carrying out ecological restoration on old lakes, dredging and sediment treatment should be carried out.